If it breaks open — if, say, he bangs into the capsule while jumping or supersonic shock waves batter him — potentially lethal bubbles could form in his bodily fluids. That's what's known as boiling blood. A Soviet military officer died in 1962 after jumping from a balloon at 86,000 feet; the visor of his helmet hit the gondola and cracked.

During the descent, the temperature could be as low as minus 70. Baumgartner's suit will be all he has between his body and the extreme cold.

Then there's the risk of a flat spin, in which Baumgartner loses control of his body during the free fall and starts spinning. A long, fast spin, if left unchecked, could turn his eyeballs into blood-soaked, reddish-purple orbs, and he could be left temporarily blind. Also, a massive blood clot could form in his brain.

As long as he keeps himself aerodynamically stable, no problems.
He's already successfully done a jump from 96 000 feet (18mi/30km).
He'll accelerate, go supersonic, then the atmosphere will slow him down to terminal velocity.
I wish him luck, it'll be interesting to watch.

Now, what would be more interesting is a jump from low earth orbit, 60mi/100km.
Anyone that goes that high gets Astronaut wings. That would be very cool.

ROSWELL, N.M. (AP) — Skydiver Felix Baumgartner's attempt at the highest, fastest free fall in history Tuesday is more than just a stunt.

His planned 23-mile dive from the stratosphere should provide scientists with valuable information for next-generation spacesuits and techniques that could help astronauts survive accidents.

Jumping from more than three times the height of the average cruising altitude for jetliners, Baumgartner hopes to become the first person to break the sound barrier outside of an airplane. His team has calculated that to be 690 mph based on the altitude of his dive.

His medical director Dr. Jonathan Clark, a NASA space shuttle crew surgeon who lost his wife, Laurel Clark, in the 2003 Columbia accident, says no one knows what happens to a body when it breaks the sound barrier.

"That is really the scientific essence of this mission," said Clark, who is dedicated to improving astronauts' chances of survival in a high-altitude disaster.

Clark told reporters Monday he expects Baumgartner's pressurized spacesuit to protect him. If all goes well and he survives the death-defying jump, NASA could certify a new generation of spacesuits for protecting astronauts, and provide an escape option, from spacecraft at 120,000 feet.

Currently, spacesuits are certified to protect astronauts to 100,000 feet, the level reached by Joe Kittinger in 1960 when he set the current free-fall record by jumping from an open gondola 19.5 miles high. Kittinger's speed of 614 mph was just shy of breaking the sound barrier at that altitude.

But whether Baumgartner, a 43-year-old Austrian military parachutist and extreme athlete, can attempt the jump depends on New Mexico's often unpredictable weather.

Winds from a cold front already delayed the jump by a day. Even the Albuquerque International Balloon Fiesta, 200 miles to the north, was forced to delay by a day its mass ascension of more than 500 balloons over the weekend. Baumgartner's jump can only be made if winds on the ground are less than 2 mph.

Midday Monday, the team remained optimistic for liftoff. The best window for the week was Tuesday and Wednesday, before another front is expected to move in.

Baumgartner is to be lifted into the stratosphere beginning around 7 a.m. MDT by a helium balloon that will stretch 55 stories high. Once he reaches his target altitude, he will open the hatch of his capsule and make a gentle, bunny-style hop.

Any contact with the capsule on his exit could tear the pressurized suit. A rip could expose him to a lack of oxygen and temperatures as low as minus 70 degrees. It could cause potentially lethal bubbles to form in his bodily fluids, a condition known as "boiling blood."

There are also risks he could spin out of control, causing other risky problems.

Despite the horrifying hazards of the dive, he and his team of experts say they have confidence in their built-in solutions and have a plan for almost every contingency. The spacesuit and capsule were tested in two early skydiving practice runs, one from 15 miles up in March and 18 miles in July.

As long as he keeps himself aerodynamically stable, no problems.
He's already successfully done a jump from 96 000 feet (18mi/30km).
He'll accelerate, go supersonic, then the atmosphere will slow him down to terminal velocity.
I wish him luck, it'll be interesting to watch.

Now, what would be more interesting is a jump from low earth orbit, 60mi/100km.
Anyone that goes that high gets Astronaut wings. That would be very cool.

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he needs to atleast reach and break 768 Miles per hour to bust the sound barrier. now with the size of him and the space suit the sonic boom will be small, compared to that of a Fighter.

Speed of sound decreases as elevation increases and as pressure and temperature both drop.

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1/2 correct. Interesting to find that altitude and pressure have virtually no effect on the speed of sound, it's almost completely dependant on temperature, not pressure See this graph:

In gases, compressibility and density are related, making other compositional effects and properties important, such as temperature and molecular composition. In low molecular weight gases, such as helium, sound propagates faster compared to heavier gases, such as xenon (for monatomic gases the speed of sound is about 75% of the mean speed that molecules move in the gas). For a given ideal gas the sound speed depends only on its temperature. At a constant temperature, the ideal gas pressure has no effect on the speed of sound, because pressure and density (also proportional to pressure) have equal but opposite effects on the speed of sound, and the two contributions cancel out exactly. In a similar way, compression waves in solids depend both on compressibility and density—just as in liquids—but in gases the density contributes to the compressibility in such a way that some part of each attribute factors out, leaving only a dependence on temperature, molecular weight, and heat capacity (see derivations below). Thus, for a single given gas (where molecular weight does not change) and over a small temperature range (where heat capacity is relatively constant), the speed of sound becomes dependent on only the temperature of the gas.

Weight and temperature of gas changes dramatically at his altitude when he jumps. Its not consistent at all. Also is he free falling (didn't read the original article) because if so what about terminal velocity? Once the density gets high enough there is no way he can break the sound barrier without propulsion.

Weight and temperature of gas changes dramatically at his altitude when he jumps. Its not consistent at all. Also is he free falling (didn't read the original article) because if so what about terminal velocity? Once the density gets high enough there is no way he can break the sound barrier without propulsion.

I sure see a correlation below the 10... seems like it increases as the altitude lowers. Yes, temperatures are there, true, but you dont see the speed of sound at XXC vs -XXC, you just see altitude. not to mention, for all intents and purposes, we are talking where airplanes can fly, not 50 miles up.

Green and Tan are pressure and density of the air, there is no correlation with speed of sound

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From your link....

Speed of sound increases with height in two regions of the stratosphere and thermosphere, due to heating effects in these regions.

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So as the density increases so does the speed of sound. I get what you saying but hes not jumping from the Thermospere. He jumping where there is air density. Just not much and the tempature is -70F there. Hes gonna hit 80F pretty damn quick. ALSO does he have any propulsion?